My father was classified as permanently and totally disabled and has still been denied for disability two times. Why?
I'm not sure what your father's situation is because you don't say who has classified him as permanently and totally disabled. Generally, "permanently and totally disabled" is a term used in workers' compensation cases as well as for disability pensions and long-term disability insurance. The definition of "permanently and totally disabled" varies depending on which type of insurance or benefit is being talked about. To make it even more complicated, the definition of permanent and total disability varies within the workers' comp world depending on the state you were injured in, and within the private insurance and pension industries, depending on which company offers the insurance or pension. In these and other disability compensation systems, such as Veterans Disability Compensation, benefits are paid dependent on the amount of disability. The highest benefit rates are reserved for permanent and total disability.
In contrast, in the Social Security Disability system, there aren't gradients, or percentages, of disability. You are either able to do "substantial" work or you're not. The inability to do substantial work, or "substantially gainful activity" to be exact, is defined as not being able to make more than $1,170 (as of 2017) per month for at least a year (but for the self-employed or those who receive modifications or assistance to be able to work, there are different tests). In other words, to get Social Security disability, you don't need to be permanently disabled, and don't necessarily need to be totally disabled (for instance, if you can work two hours per day, but only two hours per day, you could potentially still receive Social Security benefits as long as you make less than $1,170 per month). For more information, see our article answering the question, do you need to be permanently and totally disabled to get Social Security benefits?
The point I am trying to make is that it isn't useful to use the disability definition from one system, like workers' comp, in a totally different system, like Social Security Disability. The programs have little to do with each other, and the fact the your father meets the definition of disability in one industry is no guarantee that he will be approved for benefits in the Social Security system. The best thing for your father to do is figure out why disability benefits were denied to him (did he leave out important medical records?) and file a Social Security appeal.
If, on the other hand, you were referring to the fact that your father's personal physician stated that he is permanently and totally disabled, that is another story. Sometimes a doctor is asked to write a letter or fill out a form, such as a discharge from student loan obligations, stating that the patient is permanently and totally disabled.
In the Social Security disability evaluation process, a doctor's cursory note stating something to the effect of "my patient is permanently and totally disabled" is not going to be very useful to a patient seeking disability benefits. A statement of disability from a patient's treating physician can have a favorable effect on the outcome of a case, but such statements need to be detailed to the extent that they indicate the claimant's functional limitations. This is why the opinions of treating physicians are best captured on what is known as an RFC form, or residual functional capacity form.
Going back to your question, there's no real answer as to why a legitimately disabled person should be denied two times. There's no justifiable reason why there is such a huge disparity in approval rates between the lower levels of the disability determination process, which are decided at the state agency level, and the appeal hearing stage of the system, which is handled by federal administrative judges. As things stand, however, it is simply a fact of life for the average disability applicant that he or she might be denied twice.
However, disability claimants who have been denied twice -- at the initial claim and reconsideration levels -- often have a much greater chance of being approved later at a disability hearing, statistically speaking. And because someone, or some system, did classify your father as permanently and totally disabled, he obviously has serious medical issues, so he should have an excellent chance of winning Social Security disability benefits if he hires a disability lawyer to appeal his case to an ALJ hearing, and then appeal to the Appeals Council, if necessary, and even appeal the case to federal district court.